1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. In addition, the present invention relates to a process, a machine, manufacture, or a composition of matter. One embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, a driving method thereof, or a manufacturing method thereof. In particular, one embodiment of the present invention relates to a semiconductor device, a display device, or a light-emitting device each including an oxide semiconductor.
In this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. A display device, an electro-optical device, a semiconductor circuit, and an electronic device include a semiconductor device in some cases.
2. Description of the Related Art
In recent years, improvement in operation speed is required in semiconductor devices (e.g., a central processing unit (CPU) and a dynamic random access memory (DRAM)) including transistors. The resistance of a wiring connected to a transistor can be a factor that inhibits an improvement in operation speed; therefore, a reduction in wiring resistance is required.
Research and development of using copper (Cu) as a material of a wiring is extensively conducted. However, Cu is disadvantageous in that adhesion thereof to an insulating film is low and that the characteristics of a transistor easily deteriorate due to diffusion of Cu into a semiconductor region of the transistor. Note that a silicon-based semiconductor is widely known as a semiconductor applicable to a transistor, and as another material, an oxide semiconductor has attracted attention (see Patent Document 1).
Furthermore, a Cu—Mn alloy is disclosed as an ohmic electrode formed over a semiconductor including an oxide semiconductor containing indium (see Patent Document 2).